The invention provides for a method for running a computer network, especially a method for developing stable daisy-chained Ethernet loops and an arrangement for providing such loops. Furthermore, the invention provides for such a computer network.
A computer network is a collection of computers and other components interconnected by communication channels. These channels allow for sharing of resources and information. Computer networks can be classified according to a variety of characteristics as the medium used, communication protocols, scale, topology, and organizational scope.
Document WO 2010/088965 A1 shows a method for using a computer network comprising a number of bridges each having ports for receiving and sending streams. The streams are sent from a router via the ports of bridges that have shown interest to at least one receiver, whereby in case of a link failure at least one receiver sends back a message to the router. The method can be used in a so called Ethernet network.
Ethernet networks are frame-based computer networks for local area networks. It is to be noted that Ethernet networks cannot handle loops. If a loop is created, packets will continuously be communicated over the loop. Standard protocols are developed to detect loops and isolate both ends of the loops. When the network topology changes, detection is restarted to avoid creation of unconnected parts of the network or new loops.
Loops are usually created for cable and equipment redundancy using Ethernet bridges. Devices are usually star-wired to the bridges.
It can take some time before loops are detected. To avoid overload of the network by circling packets, the default in loop detection protocol is that there is no link. This means that there is no communication until the network topology is correctly detected. The best known protocols are Spanning Tree Protocol and Rapid Spanning Tree Protocol.
The Spanning Tree Protocol (STP) is a network protocol that ensures a loop-free topology for bridged Ethernet networks. STP is adapted to prevent bridge loops and broadcast radiation. For this, it creates a spanning tree within a mesh network of connected-2-bridge layers, e.g. Ethernet bridges, and disables those links that are not part of the spanning tree, leaving a single active path between any two network nodes.
The Rapid Spanning Tree Protocol (RSTP) provides for significantly faster spanning tree convergence after a topology change introducing new convergence behaviour and bridge port rules.
STP takes more than 30 seconds to recreate the network topology, RSTP takes 2 seconds or less in case of physical link failure.
Audio networks can require a daisy-chained solution for its end devices. This is solved in a standard way by adding an Ethernet bridge with at least three ports to each device. Typically, in audio network the number of devices being daisy-chained is specified large, e.g. 20. Redundancy is an important feature for audio networks. Therefore, it must be possible to create a loop with a chain of 20 devices. Each device in the audio network is an end device, e.g. a loudspeaker.
Daisy chain is a wiring scheme in which multiple devices are wired together in sequence or in a ring. Each of the network devices includes an upstream port and a downstream port, whereby each port is coupled to a cable. A third port in each device is adapted to receive traffic from and transmit traffic to the network.
Document EP 1 720 293 A 1 shows a method for providing redundancy in a daisy chain local area network. The method comprises the steps of forming in each network device a passive signal path, connecting pins of an upstream port associated with the normally used twisted pairs of a Cat 5 cable to pins of a downstream port associated with the normally unused twisted pairs of the Cat 5 cable, forming loop back connections at the terminal network devices, and implementing a Spanning Tree Protocol in each of the network devices for defining an active signal path through the local area network.